منابع مشابه
Broadband RF Pulses with Polynomial-Phase Response
Introduction Broad-bandwidth radio-frequency (RF) pulses are important for various kinds of MR experiments. The achievable RF field strength B1 of the transmitting system is limited on whole-body scanners, leading to small bandwidths of regular amplitude-modulated RF pulses. In order to increase the bandwidth, pulses with inherently reduced maximum B1 amplitude (B1max) are necessary. Overlaying...
متن کاملEffects of relaxation during RF pulses on the homogeneity of signal intensity in parallel transmission
Introduction: Counteracting the inhomogeneity of the RF excitation is one of the technical challenges in high-field MRI. Dynamic RF shimming techniques in combination with parallel transmission have shown to be quite powerful for mitigating B1 inhomogeneity [1, 2]. So far to our knowledge, these methods have been uniquely based on the spins’ coherent dynamics, and do not account for relaxation ...
متن کاملSimultaneous multislice imaging with slice-multiplexed RF pulses.
A method for simultaneous multislice imaging is presented that uses a multislice RF pulse that imparts a different linear phase profile to each slice. During readout, slices are unaliased by using extra slice-select gradient lobes, which rephase and dephase individual slices one at a time. Compared to other simultaneous slice methods, this method avoids distortion by slice-select gradients, and...
متن کاملT2*-compensated Transmit SENSE RF pulses
Introduction Selective excitation in more than one dimension is plagued by effects that are due to the long duration of the RF pulses and gradient trajectories needed. B0 off-resonances, for example, dephase magnetization contributions created at different points in time during the excitation process. As a consequence, these contributions do not add up consistently which causes artifacts in the...
متن کاملSuppression of banding and transient signal oscillations in balanced SSFP using a spoiled RF pre-phasing approach
The ideal excitation pattern produced by the B1a sub-pulse has uniform intensity and an in-plane phase variation θ(x,y) = –πΔf(x,y) TR. To produce such a pattern it is necessary to use either multiple transmit coils as proposed in [1], a 3D RF pulse as done here, or a combination of the two. In this work a slice-selective tip-down pulse (B1a) with 2D in-plane phase variation was designed using ...
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ژورنال
عنوان ژورنال: Magnetic Resonance in Medicine
سال: 2009
ISSN: 0740-3194
DOI: 10.1002/mrm.22116